I'm planning to slowly upgrade my sailboat to a 48v system for electrification, and I'd like AC shore power as soon as possible, hence I'm looking at a new-style Multiplus. If I get the 48v version, would that be able to charge my current 12v bank until I upgrade the batteries? I couldn't get a clear answer to this from the manual.
The 48V MultiPlus will only work on a 48V battery system.
Likewise, the 12V models are for 12V batteries and 24V models for 24V batteries.
Inverters / MultiPlus are not flexible with battery Voltages like the MPPT's are.
With "work" do you mean the charger or the inverter? I don't care about the inverter right now, if it works with shore power but can keep my 12v alive I'm happy.
In the MultiPlus / Quattro, the Inverter / Charger is one module, a converter if you like. One transformer arragement with its power pack. It's not made up of a separate charger and a separate inverter.
So, a 48V MultiPlus / Quattro is designed to charge or invert from a 48V battery only.
The MultiPlus needs a battery bank to work from and won’t power up unless connected to a DC source. So a 48v model needs a 48v bank.
That said it does have a 12v trickle charger, so if you put a new bank in it can trickle charge (4Amp) your existing 12v bank.
If you have the space and money, use the new MultiPlus at 48v with a new bank and a DC/DC charger to charge the 12v bank.
I know that is extra cost, but the only way to go.
It won't power up at all, as in it won't pass through shore power if not connected to a battery bank? Am I understanding that correctly? That seems strange – if my bank is dead for some reason I'd still want the AC power to work while plugged in.
Disregarding the above, the trickle charge could actually be enough. I'll look into that, thanks!
Thank you. Sorry to keep having to dig for specifics, but why is it not recommended? I understand that it will mean I could potentially lose power if shore AC goes out, which is fine, but is there more to it than that?
Hi @ctolsen
Because the battery dampens the DC ripple and without a battery the capacitors have to do everything.
In practice it won't be a problem for a short time, but we don't advice it.
Hi @Daniël Boekel (Victron Energy Staff)
for the interim could @ctolsen use a dc-dc convertor (Orion?) to charge his 12v bank from the 48v charger in the multi ? would he still need the 48v batteries for the DC ripple to not be a problem ?
Hi @Marky01
That doesn't make much sense... just use a 12V charger...
Hi I am converting a sailboat to Electric drive. 48V traction battery bank with 12V service/instrumentation battery. I want to be able to move power both ways. 48V > 12 V using an isolated Orion Tr 48-12 Converter. 12V > 48V I am considering using two Isolated Orion Tr Smart 12-24/10 DC-DC chargers connected in series. This gives 2x24V = 48V with 200V isolaton. I expect the current to be 10A so total power transferred 500W. Question 1: Am I on the right track? Question 2: Can you suggest a better / simpler / more elegant solution ? Many thanks MK
why would you want to go from 12V to 48V?
Use 48 bank as primary battery and go down to 12V from there.
I don't know if two DCDC converters in series is a good idea.
Hi Daniel, Charging the 48V traction battery was plan A. BUT its a small boat so all the panels are small (20-90W) and will not reach 48V ever. This forces the need for Boost MPPT controllers, which are crazy expensive and rare with no GX/Victron Connect. (Victron does not offer a boost MPPT, (A missing Victron marine product.............).
Plan B was to find a 2-way 48V 12V DC/DC converter. They do exist, they are not cheap. That would allow smooth operation of both banks with priority to instrumentation. This approach is supported in the RV world. A few products exist. Some more sophisticated heavy and expensive than others. Could be controled from GX VF contact, but no remote setup/monitoring. (Another missing Victron RV/marine product.........)
Plan C, using 1x Tr 48-12 (buck) + 2 x Tr 12-24 (boost) facilitate both directions controlled with a volt free contact from Cerbo GX. Its less capable than a proper two way DC/DC RV system but simplicity and serviceability is a plus.
Given that Victron does not offer the two way capability in 12V - 48 and given the two 12-24 Booth converters are both isolated to 120V and operates from same 12V source, and On/Off VF contact will be operated simultaneously from 12V side means that each 12-24 Booster will just see an non-inductive battery load.
Its a workaround, but with small panels and priority to the instrumentation battery its a better solar harvesting solution.
Also the traction battery to instrumentation battery Tr 48V-12V buck converter is easy to control and will again ensure instrumentation battery priority.
All at the cost of 1.5Kg / 400 EUR. Until Victron makes a smart 2 way 12/48/12 DC/DC converter with GX-CAN interface which would be perfect for RV/Marine. systems build on a 48V rail.
PS: The 12V to 48V feed will predominantly ensure SOC is maintained across the whole boat in periods of no shore power / no use. The traction battery will predominantly be recharged from shore power using a Multiplus. The Multiplus will also supply 230V for cooking subject to SOC. With a total of 6KWh bank there will be enough power for a long weekend predominantly under sail.
So is it a good idea? NO, BUT you have at least two gaps in your product line up. Both would solvemy problem and both would be a good idea for Victron ;)
Apologise for the long explanation,
Mike
